Method to control configuration change times in a wireless device

ABSTRACT

A method to control configuration change times is performed at a mobile wireless communication device when the mobile wireless communication device is connected to a wireless network. The mobile wireless device is connected in a first configuration mode. The mobile wireless communication device receives a control message from a radio network subsystem in the wireless network at a local receive time. The received control message includes a time indication for when to start a configuration mode change of the mobile wireless communication device, which the device extracts from the control message. The mobile wireless communication device reconfigures to a second configuration mode, different from the first configuration mode, based on the extracted time indication and the local receive time.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior U.S. application Ser. No.12/779,907, filed May 13, 2010, entitled “METHOD TO CONTROLCONFIGURATION CHANGE TIMES IN A WIRELESS DEVICE”, by Shi et al. and isincorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

The described embodiments relate generally to wireless mobilecommunications. More particularly, a method is described for controllingconfiguration change times in a mobile wireless communication device.

BACKGROUND OF THE INVENTION

Mobile wireless communication devices, such as a cellular telephone or awireless personal digital assistant, can provide a wide variety ofcommunication services including, for example, voice communication, textmessaging, internet browsing, and electronic mail. Mobile wirelesscommunication devices can operate in a wireless communication network ofoverlapping “cells”, each cell providing a geographic area of wirelesssignal coverage that extends from a radio network subsystem located inthe cell. The radio network subsystem can include a base transceiverstation (BTS) in a Global System for Communications (GSM) network or aNode B in a Universal Mobile Telecommunications System (UMTS) network.Whether idle or actively connected, a mobile wireless communicationdevice can be associated with a “serving” cell in a wirelesscommunication network and be aware of neighbor cells to which the mobilewireless communication device can also associate. The quality of acommunication link between the mobile wireless communication device andthe radio network subsystem can vary based on the distance between themand on interference included in received signals at either end of thecommunication link. As the mobile wireless communication device movesfurther away from an associated radio network subsystem, eventually aneighbor cell can provide an equal or better performing communicationlink than the current serving cell. The mobile wireless communicationdevice can include a process for determining if and when to switch cellswith which it associates. If the mobile wireless communication device isactively connected to the serving cell, then the process of switching toa neighbor cell is known as “handoff.”

To detect the presence of neighbor cells and to determine an expectedquality of communication links to detected neighbor cells, the mobilewireless communication device can listen to messages periodicallybroadcast by radio network subsystems located in the neighbor cells.Radio network controllers in the wireless communication network canmanage handoff of the mobile wireless communication device betweendifferent cells based on measurements taken by the mobile wirelesscommunication device when listening to the periodically broadcastmessages. In certain wireless communication networks, transmit andreceive frequency spectra used by mobile wireless communication devicein the serving cell can overlap transmit and receive frequency spectraused in neighbor cells. If the mobile wireless communication devicetransmits and receives continuously with the network subsystem locatedin the serving cell, then the mobile wireless communication device canbe unable to listen to broadcast messages sent by neighbor cells thatoccupy the same frequency spectra. In order to suppress transmissionsbetween the mobile wireless communication device and the networksubsystem in the serving cell with which the mobile wirelesscommunication device can be associated, network controllers in thewireless network can initiate an operating mode that includes quietperiods during transmissions that can be used for measurement. In a UMTSnetwork using wideband code division multiple access (WCDMA) technology,such a transmission mode is referred to as a “compressed” mode.

A network controller can communicate parameters to the mobile wirelesscommunication device in a network control message that can specify timeperiods for a “compressed” mode. The network control message can includea time indication for when the mobile wireless communication device andthe serving cell's radio network subsystem can start and end. Timeindications can be based at least partially on time synchronizationcounters maintained at the mobile wireless communication device and theradio network subsystem. Because both the serving cell's radio networksubsystem and the mobile wireless communication device should enter the“compressed” mode simultaneously, the network control message start timeindication can be at a future time, thereby allowing both the servingcell's radio network subsystem and the mobile wireless communicationdevice time to prepare for changing transmission modes. The timerequired to transmit the entire network control message from the servingcell radio network subsystem to the mobile wireless communication deviceas a series of discrete packets, however, can be indeterminate. Eachdiscrete packet in the network control message can be corruptedindividually during transmission to the mobile wireless communicationdevice and require re-transmission by the radio network subsystem. Withsufficient time delays in transmission, the “future” time indicationthat specifies when to start the “compressed” mode can refer to a “past”time, i.e. the radio network subsystem can enter “compressed” modebefore the mobile wireless communication device. Additionally, timesynchronization counters maintained at the mobile wireless communicationdevice and the radio network subsystem can be based on a digital counterhaving a finite length, and thus the time synchronization counters can“roll over” after a period of time. The mobile wireless communicationdevice can interpret the time indications for starting the “compressed”mode as a future time when they actually can indicate a past time. Themobile wireless communication device and the serving cell radio networksubsystem can start and end compressed modes at each end of acommunication link between them at different times resulting inmisaligned compressed mode time intervals and potentially incurringtransmission errors. Similar errors can occur for a configuration changemessage from the serving cell radio network subsystem that includes atleast a start time indication based on finite length timesynchronization counters.

Thus there exists a need to control configuration time changes between amobile wireless communication device and a radio network subsystem thataccounts for transmission delays and time synchronization countervalues.

SUMMARY OF THE DESCRIBED EMBODIMENTS

The described embodiments relate generally to wireless mobilecommunications. More particularly, a method is described for controllingconfiguration change times in a mobile wireless communication device.

In one embodiment, a method to control configuration change times isperformed at a mobile wireless communication device when the mobilewireless communication device is connected to a wireless network.Initially, the mobile wireless device is connected in a firstconfiguration mode. The mobile wireless communication device receives acontrol message from a radio network subsystem in the wireless networkat a local receive time. The received control message includes a timeindication for when to start a configuration mode change of the mobilewireless communication device, which the device extracts from thecontrol message. The mobile wireless communication device reconfiguresto a second configuration mode, different from the first configurationmode, based on the extracted time indication and the local receive time.

In a further embodiment, messages communicated between the mobilewireless communication device and the network subsystem are formed usingmultiple consecutive frames. Incorrectly received frames in a messagecan result in retransmissions, thereby extending the time to receivecorrectly a complete message. The mobile wireless communication devicedetermines if the extracted time indication precedes the local receivetime and reconfigures to the second configuration mode immediately.

In another embodiment, a mobile wireless communication device includes awireless transceiver and a processor coupled to the wirelesstransceiver. The wireless transceiver receives messages from a wirelessnetwork subsystem, including a configuration mode change message thatincludes a time indication for the start of a configuration mode changefrom a first configuration mode to a second configuration mode. Theprocessor is arranged to execute instructions for extracting the timeindication from the received configuration mode change message. Theprocessor compares the extracted time indication to a local receive timewhen the configuration mode change message is correctly received. Theprocessor reconfigures the wireless transceiver to the secondconfiguration mode at a time different from the time indicated in theconfiguration mode change message.

In a further embodiment, a computer program product encoded in acomputer readable medium for reconfiguring a mobile wirelesscommunication device connected to a wireless network is described. Thecomputer program product includes non-transitory computer program codefor receiving a control message from a radio network subsystem in thewireless network. The control message includes a time indication forwhen to start a configuration mode change. Non-transitory computerprogram code controls a transceiver in the mobile wireless communicationdevice to transmit and receive messages as a series of consecutiveframes. Values for a local frame counter in the mobile wirelesscommunication device are calculated modulo an integer N, while valuesfor an extended local frame counter are calculated modulo an integerM>N. First and second values for the extended local frame counter aredetermined for the first and last received frames of the controlmessage. The mobile wireless communication device is reconfigured at atime earlier than indicated by the time indication in the controlmessage when the difference between the second and first extended localframe counters is at least equal to the integer value N.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and the advantages thereof may best be understood byreference to the following description taken in conjunction with theaccompanying drawings.

FIG. 1 illustrates a mobile wireless communication device located withina wireless cellular communication network.

FIG. 2 illustrates a hierarchical architecture for a wirelesscommunication network.

FIG. 3 illustrates a state transition diagram for a mobile wirelesscommunication device.

FIG. 4 illustrates a mobile wireless communication device measuringsignals in a wireless cellular communication network.

FIG. 5 illustrates a compressed mode transmission pattern for a mobilewireless communication device.

FIG. 6 illustrates a measurement message sequence between a userequipment (UE) and a radio network subsystem (RNS).

FIG. 7 illustrates a packet transmission sequence with re-transmissionbetween a UE and an RNS.

FIG. 8 illustrates aligned and misaligned compressed mode intervals fora UE and an RNS.

FIG. 9 illustrates synchronization frame counter value alignment withthe packet transmission sequence of FIG. 7.

FIG. 10 illustrates partially aligned compressed mode intervals for a UEand an RNS.

FIG. 11 illustrates a method for controlling a configuration time changein a mobile wireless communication device.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following description, numerous specific details are set forth toprovide a thorough understanding of the concepts underlying thedescribed embodiments. It will be apparent, however, to one skilled inthe art that the described embodiments may be practiced without some orall of these specific details. In other instances, well known processsteps have not been described in detail in order to avoid unnecessarilyobscuring the underlying concepts.

FIG. 1 illustrates a wireless communication network 100 of overlappingwireless communication cells to which a mobile wireless communicationdevice 106 can connect. Each wireless communication cell can cover ageographic area extending from a centralized radio network subsystem104. The mobile wireless communication device 106 can receivecommunication signals from a number of different cells in the wirelesscommunication network 100, each cell located at a different distancefrom the mobile wireless communication device. As the signal strength ofa wireless communication signal decays proportionally to the square ofthe distance between a transmitting end and a receiving end, the mobilewireless communication device 106 can measure the received signalstrength from several different cells in the wireless communicationnetwork 100. Measurements of received signal strength can becommunicated from the mobile wireless communication device 106 to thewireless communication network 100, and radio network controllers (notshown) in the wireless communication network 100 can manage a “handover”of the mobile wireless communication device 106 between different cellsas received signal strengths change.

During a “handover” between cells, radio communication links between themobile wireless communication device 106 and the wireless communicationnetwork 100 can change. For a “hard” handover, minimal or no overlaptime between old and new radio communication links can exist; “hard”handovers can occur when changing the radio communication link carrierfrequency used for transmissions between the mobile wirelesscommunication device 106 and the wireless communication network 100. Themobile wireless communication device 106 can initially receivetransmissions from a serving cell 102. As the mobile wirelesscommunication device 106 moves farther from the radio network subsystem104 in the serving cell 102 (resulting in decreasing receive signalstrength at the mobile wireless communication device 106 from the radionetwork subsystem 104) and closer to the radio network subsystem 108 ina neighbor cell 110 (resulting in increasing receive signal strengthfrom the radio network subsystem 108), a “hard” handover between theserving cell 102 and the neighbor cell 110 can occur when receive signalstrengths measured at the mobile wireless communication device 106 crosscertain thresholds. In a representative embodiment, the “hard” handovercan occur when the receive signal strength of the neighbor cell 110exceeds the signal strength of the serving cell 102. “Soft” handoverscan also be used to ease the transition between cells. During a “soft”handover, a new radio link can be added before the old radio link isremoved, also based on measured signal strengths, although thethresholds can differ from those used for “hard” handovers. Handoverscan also occur between two different wireless communication networks,including when each network uses a different wireless communicationtechnology. For example, a handover can occur between two different 3Gnetworks, or between a 2G and a 3G network, which can be referred to asan inter-RAT (radio access technology) handover. Handovers can requirecoordination between the mobile wireless communication device 106 andthe radio network subsystems 104 of the wireless communication network100 to ensure a smooth and seamless transition.

FIG. 2 illustrates a hybrid hierarchical architecture 200 for a wirelesscommunication network that includes both UMTS and GSM access networkelements. A mobile wireless communication device 106 operating in a GSMwireless communication network can be referred to as a mobile station(MS) 204, while a mobile wireless communication device 106 operating ina UMTS network can be referred to as user equipment (UE) 202. (Wirelessmobile communication devices 106 can include the capability ofconnecting to multiple wireless communication networks that usedifferent wireless radio network technologies, such as to a GSM networkand to a UMTS network; thus the description that follows can also applyto such “multi-network” devices as well.) The MS 204 can connect to theGSM wireless communication network through a radio network subsystemknown as a base station subsystem (BSS) 218. The BSS 218 can include abase transceiver station (BTS) 220 that transmits and receive radiofrequency signals between the MS and the wireless communication networkand a base station controller (BSC) that manages the communicationbetween a core network 236 and the MS 204. In a GSM wirelesscommunication network, an MS 204 can be connected to one BSS at a time.As the MS 204 moves throughout the GSM wireless communication network,the BSC 222 can manage handover of the MS 204 to different BTS 220located in different cells. The GSM radio access network BSS 218connects to a centralized core network 236 that provides circuitswitching and packet switching capabilities.

The core network 236 can include a circuit switched domain 238 that cancarry voice traffic to and from an external public switched telephonenetwork (PSTN) and a packet switched domain 240 that can carry datatraffic to and from an external public data network (PDN). The circuitswitched domain 238 can include multiple mobile switching centers (MSC)228 that connect a mobile subscriber to other mobile subscribers or tosubscribers on other networks through gateway MSCs (GMSC) 230. Thepacket switched domain 240 can include multiple support nodes, referredto as serving GPRS support nodes (SGSN) 224, that route data trafficamong mobile subscribers and to other data sources and sinks in the PDN234 through one or more gateway GPRS support nodes (GGSN) 226. The corenetwork 236 can be commonly used by multiple radio link access networksubsystems that use different radio link technologies. As shown in FIG.2, both a UMTS terrestrial radio access network (UTRAN) 214 and a GSMBSS 218 can connect to the same core network 236.

The circuit switched domain 238 and the packet switched domain 240 ofthe core network 236 can each operate in parallel, and both domains canconnect to different radio access networks simultaneously. The UTRAN 214in the UMTS wireless access network can include multiple radio networksubsystems (RNS) 216. Each RNS 216 can include a “Node B” 206/210 thattransmits and receives radio frequency signals and a radio networkcontroller (RNC) 208/212 that manages communication between the “Node B”206/210 network elements and the core network 236. Unlike the MS 204 inthe GSM radio access network, the UE 202 can connect to more than oneradio network subsystem (RNS) 216 simultaneously. One RNS 216 caninclude a “serving” radio network controller (SRNC) 208 that maintainsthe logical connection between the UE 202 and the core network 236through a primary Node B 206. A second RNS 216 can include a “drift”radio network controller (DRNC) 208 that provides additional radio linkresources through a secondary Node B 210 that supplements the radio linkthrough the primary Node B 206. When connected to more than one RNS 216,the UE 202 can be considered to be in a “soft” handover state. Theserving RNC 208 can provide a single connection point for communicationbetween the UE 202 and the core network 236, including traffic thatpasses through the secondary Node B 210 and the drift RNC 212.

A “soft” handover can be used to transfer a connection of the UE 202seamlessly between different Node B's located in different RNS's 216.Handover can also be used to manage adding and deleting radio linksbetween the UE 202 and the UTRAN 214 to change a connection. In order todetermine properties of radio frequency signals received at the UE 202,the RNS 216 can use measurements taken by the UE 202 and communicatedback to the RNS 216 through measurement control messages. For example,consider the wireless communication network 100 in FIG. 1 to be a UMTSwireless network. The radio network subsystem 104 in the serving cellcan direct the mobile wireless communication device 106 to measure theradio network subsystem 108 in neighbor cell 110 as well as other radionetwork systems located in nearby neighbor cells.

A UMTS wireless communication network can use a wireless communicationradio link technology known as wideband code division multiple access(W-CDMA). W-CDMA transmissions can occupy a relatively wide bandwidthbased on a direct sequence spread spectrum modulation. Transmissionsbetween a UE 202 and an RNS 216 in a UMTS network can be modulated by aspreading code, and each UE 202 connected to the RNS 216 can use adifferent spreading code but transmit simultaneously using the samefrequency spectrum. Received signals can be demodulated by correlatingthem with a correctly matched de-spreading code. As the set of spreadingcodes used in W-CDMA can be mutually orthogonal, signals intended for aparticular UE can be separated from signals transmitted to other UE,even though all of the signals can overlap and use the same frequencyspectrum simultaneously. UMTS spread spectrum signals can occupy a wider5 MHz channel bandwidth compared with a narrower 200 kHz channelbandwidth used by GSM signals.

FIG. 3 illustrates a state diagram 300 that includes several differentstates in which a mobile wireless communication device 106 can exist.After a “power on” initialization, the mobile wireless communicationdevice 106 can search for nearby access network sub-systems, such as abase station subsystem BSS 218 for a GSM network or an RNS 216 in aUTRAN 214 for a UMTS network. The mobile wireless communication device106 can measure received radio signals at different frequencies when notconnected to a particular network. The measurements can be used todetermine signal strengths and quality for different available nearbycells. The mobile wireless communication device 106 can “camp” on a cellin the GSM or UMTS network in an idle mode 324. On the GSM network, themobile wireless communication device 106 (equivalently the mobilestation MS 204) can transition between a GSM “camped” state 314 and aGSM “connected” state 316 by establishing and releasing radio resources322 through communication with the BSS 218. Similarly on the UMTSnetwork, the mobile wireless communication device 106 (equivalently theuser equipment UE 202) can change between a UTRAN “camped” state 312 anda UTRA radio resource control “connected” state 310 by establishing andreleasing radio resource control 320 through communication with the RNS216 in the UTRAN 214. The UMTS UE 202 can be in one of four distinctstates when connected to the UMTS network. In a cell DCH (dedicatedchannel) state 306, the UE 202 can be allocated a dedicated physicalchannel in both the uplink and downlink directions including transportchannels to transmit and receive in both directions. In a cell FACH(forward access channel) state 308, the UE 202 can have no dedicatedphysical channel allocated but can monitor a common downlink FACH andtransmit on a common shared transport uplink channel. In a cell PCH(paging channel) state 304, the UE 202 can have no dedicated physicalchannel allocated but can monitor a common pace indicator channel (PICH)with no uplink activity possible. A URA (UTRAN registration area) PCHstate 302 resembles the cell PCH state 304, except that the UE 202 canbe known to the UMTS network based on a broader “URA” level rather thanon a narrower “cell” level. A URA can consist of multiple cells in aUMTS network.

As geographic areas for different wireless networks can overlap andcover different regions, a multi-network capable mobile wirelesscommunication device 106 can maintain a continuous connection whenswitching between a UMTS network and a GSM network by using an inter-RAThandover 318. When connected to the UMTS network, communication betweenthe UE 202 and the UMTS network using W-CDMA can be continuous, thus notpermitting silent periods in which to listen for and measure signalsfrom other cells in the same network (or cells in a different network).The continuous W-CDMA transmissions differ from time division multipleaccess (TDMA) transmissions where only certain time slots can be used bythe mobile wireless communication device 106 when connected, while othertime slots remain open for use by other wireless communication devices.The “idle” time slots can permit the wireless communication device 106opportunities to listen for signals broadcast by radio networksubsystems other than the one to which it is connected. As illustratedin FIG. 4, a mobile wireless communication device 402 can be connectedto a radio network subsystem 404 in a serving cell 406 using a carrierfrequency f₁. A neighbor cell 410 can contain a radio network subsystem408 that transmits on a different carrier frequency f₂, while a neighborcell 414 can contain a radio network subsystem 412 that transmits on acarrier frequency f₃. In order to detect and measure transmissions fromradio network subsystems 408 and 412, the receiver in the mobilewireless communication device 402 can be tuned to each radio networksubsystem's frequency f₂ and f₃ intermittently. When the mobile wirelesscommunication device 402 is in an “idle” state, frequency tuning of thedevice's receiver can be used because no active connection exists;however, when the mobile wireless communication device is in a“connected” state, gaps in transmissions (i.e. a compressed mode) can becreated so that the mobile wireless communication device 402 can listen.

FIG. 5 illustrates a representative frame structure 500 for compressedmode transmissions. The compressed mode can be uniquely defined by a setof parameters communicated to the UE 202 by the UMTS network.Communication between the UE 202 and the UMTS network can be divided ina sequence of successive frames, each frame occupying a uniform timeinterval of 10 ms. Each 10 ms frame can be subdivided into multiple timeslots, and in an uncompressed mode transmissions can continuously occupyall time slots. In a compressed mode, certain frames can include timeslots with no transmission. In a representative embodiment, thecompressed mode can be specified by a repeated transmission gap pattern(TGP) of frames, each TGP having a transmission gap pattern length(TGPL) 512 of consecutive frames. The TGP can repeat a transmission gappattern repetition count (TGPRC) number of times during the compressedmode. Within a transmission gap pattern, two different transmission gapscan be specified. A first transmission gap can start in the first 10 msframe of the transmission gap pattern at a transmission gap startingslot number 508 and can span a first transmission gap length 502. Timeslots within the first transmission gap can carry no transmittedsignals, while surrounding time slots in the same 10 ms frame thatcontains the first transmission gap can be boosted in signal power tocompensate. By boosting transmission segments adjacent to thetransmission gap, a constant data transfer rate can be maintained. Thetransmission gap pattern can include a second transmission gap having asecond transmission gap length 504 starting at a transmission gap startdistance 510 after the start of the first transmission gap. Asillustrated in FIG. 5, transmission gaps can be contained within asingle 10 ms frame (as shown for the first transmission gap) or straddletwo adjacent 10 ms frames (as shown for the second transmission gap). Aminimum number of time slots in each 10 ms frame can be required toensure that boosted transmission segments 506 can stay beneath a peakpower level and that a constant data transfer can be achieved acrossframes with and without transmission gaps. Compressed mode can be applyto both uplink and downlink directions. An uplink compressed mode canoccur, for example, if the frequency to measure is close to a frequencycurrently in use in the uplink direction to prevent inter-frequencyinterference during a measurement of received signals in the downlinkdirection. The specific parameter values used to specify a compressedmode can vary based on the location of the UE 202 within a UMTS networkand also based on properties of the UMTS network. For example, thenumber of frequencies to measure can depend on the network topology,such as the number and density of cells in a region, with morefrequencies available to measure requiring a longer time to be allocatedfor measurement.

A radio network subsystem (RNS) 216 in the UMTS network, to which the UE202 is actively connected, can determine when to enter a compressed modeto undertake measurements. As shown by a message exchange sequence 600in FIG. 6 between a UE 202 and an RNS 216, a measurement report 602 canbe sent to the RNS 216. Measurements reports can be sent by the UE 202in response a request from the RNS 216 or independently as a regular orsporadic update from the UE 202. The measurement report 602 can describeproperties of signals received by the UE 202 while connected to the RNS216. Based on the values received in the measurement report 602, the RNS216 can command a measurement period that uses a compressed mode bysending a measurement control message 604 to the UE 202. Measurements atthe UE 202 using the compressed mode can be for a different UMTSfrequency than currently used, or for a GSM frequency, or for a radiolink frequency using another transmission protocol. The measurementcontrol message 604 can include a time indication when the compressedmode should start and end, as well as a transmission gap pattern asshown in FIG. 5. (The measurement control message 604 can also notinclude a time indication when the compressed mode should end, in whichcase, a second measurement control message can be sent to exit thecompressed mode.) Both the UE 202 and the RNS 216 are expected to startand end the compressed mode at the same time. Time synchronizationbetween the UE 202 and the RNS 216 can be maintained by using framecounters at each end of the radio link between them. A radio networkcontroller associated with the RNS 216 in the serving cell can maintaina system frame number (SFN) counter that increments once per 10 msframe. In a representative embodiment, the SFN counter can have a lengthof 12 bits, and thus values for the SFN counter can “roll over” every40.96 seconds. The RNS 216 can transmit SFN counter values at regularintervals over a broadcast channel, such as a broadcast control channel(BCCH) in a UMTS network. The UE 202 can maintain time synchronizationat a physical channel layer 1 level using the broadcast SFN countervalues.

The UE 202 and the RNS 216 can also maintain time synchronization athigher level layers (medium access control (MAC) layer 2, radio linkcontrol (RLC) layer 2, and radio resource control (RRC) layer 3) using aconnection frame number (CFN) counter derived locally at each end of aconnection between the UE 202 and the RNS 216 based on the layer 1 SFNcounter. In a representative embodiment, the CFN counter can have alength of 8 bits, and thus values for the CFN counter can “roll over”every 2.56 seconds (substantially shorter than the SFN counter “rollover”). When the UE 202 is connected to the RNS 216 in the Cell DCH 306state, the CFN counter value can be related to the SFN counter value asCFN=(SFN−(DOFF div 38400))mod 256, where DOFF can be an offset valuesupplied by the radio network controller in the RNS 216 whenestablishing a connection with the UE 202. When the UE 202 is in a CellFACH 308 state, the CFN counter value can be computed from the SFNcounter value as CFN=SFN mod 256 (i.e. the 8 least significant bits ofthe 12 bit SFN value). An “extended” CFN value can also be calculated ineither the Cell PCH 306 state or the Cell FACH 308 state by using all 12bits rather than only the least significant 8 bits, i.e. the sameequations as above excluding the modulo 256 operation.

In the measurement control message 604 sent by the RNS 216 to the UE202, a CFN value can be included as a time indication of a frame whenthe UE 202 and the RNS 216 should start compressed mode. As indicated inFIG. 5, compressed mode can start at a particular time slot (based onthe transmission gap starting slot number 508) in the frame indicated bythe CFN value included in the measurement control message 604. If the UE202 can receive and interpret the measurement control message 604 in atimely manner, then the UE 202 and the RNS 216 can enter compressed modeat the same time. Over a “good” radio link, the measurement controlmessage 604 can be received in less than 100 ms, and with promptprocessing at the UE 202 the compressed mode can be entered in much lessthan the 2.56 second “roll over” period of the CFN counter. Themeasurement control message 604 sent by the RNS 216 can be a layer 3signaling data unit (SDU) transmitted over the radio link to the UE 202as a sequence of layer 2 protocol data units (PDU). A layer 2 protocolhandler at the UE 202 can ensure that all of the PDUs of the SDU arereceived correctly, before reassembling the layer 3 SDU. In arepresentative embodiment of the layer 2 protocol, receipt by the UE 202of each layer 2 PDU can be acknowledged to the sending RNS 216. Withoutacknowledgement from the UE 202, the PDU can be retransmitted untilsuccessfully received by the UE and acknowledged to the RNS 216. Inanother representative embodiment of the layer 2 protocol, each PDU cancontain a sequence number, and the UE 202 can request retransmission ofspecific missing PDUs based on the sequence numbers of PDUs received atthe UE 202.

If the measurement control message 604 is delayed by retransmissions,then the frame indicated by the CFN value in the delayed measurementcontrol message 606 can be in the past rather than in the future asintended. With a delayed measurement control message 606, the UE 202 andthe RNS 216 can enter and exit compressed mode at different timespotentially resulting in transmission errors over the radio linkconnection. For example, if the delayed measurement control message 606specifies a CFN value of 100 for the start of a compressed mode period,the RNS 216 can enter the compressed mode at a CFN value of 100, whilethe UE 202 can enter the compressed mode at a subsequent CFN value of100 after a roll over of one or more multiples of 256 frames (roll overtime interval).

FIG. 7 illustrates a representative sequence 700 of message transferbetween the UE 202 and the RNS 216, in which an SDU includes three PDUs,each PDU having a unique sequence number. The first and third PDUs (PDU1702, PDU3 706) can be received successfully at the UE 202 as shown,while the second PDU (PDU2 704) can be corrupted during transmission andnot be received successfully at the UE 202. The UE 202 can requestretransmission 708 of the missing PDU2 704, and the RNS 216 cansubsequently retransmit PDU2 710. Without retransmission, the SDU can besuccessfully received by the UE 202 in a “normal” time interval 712, butwith retransmission, the SDU can be successfully received by the UE 202over an “extended” time interval 714. The end of the extended timeinterval 714 can occur after the frame indicated by the CFN valueembedded in the SDU in which compressed mode should start. Multipleretransmissions can extend the time for successfully receiving an SDUconsiderably resulting in a misalignment of compressed modes at each endof a radio communication link.

With delayed receipt of the complete SDU, the UE 202 and the RNS 216 caneach start and end a compressed mode misaligned in time, as illustratedin FIG. 8. Time line 800 illustrates a measurement control message 802successfully transmitted by the RNS 216 and received by the UE 202 at atime before the time (CFN value) indicated in the measurement controlmessage 802. For the time line 800, the UE 202 and RSN 216 can start andend compressed mode aligned together. Time line 810 illustrates ameasurement control message 804 delayed by retransmission until afterthe CFN value. For the time line 810, the UE 202 and the RNS 216 canstart and end compressed mode at different times, and the compressedmode periods can be thus misaligned. As shown in FIG. 8, the RNS 216 canenter and end compressed mode earlier than the UE 202, resulting inerror prone time segments 806. During the error prone time segments 806,one side of the connection can be in compressed mode, while the othercan be not in compressed mode. For the error prone time segments 806,one side of the connection can expect transmissions with continuousframes, while the other side can expect frames that include transmissiongaps. This compressed mode misalignment can result in incorrectreception of transmitted signals at the UE 202 and at the RNS 216.

The UE 202 can minimize a misalignment of compressed mode time intervalsby using knowledge of the time required to receive the entiremeasurement control message SDU from the RNS 216. Layer 2 processing inthe UE 202 can re-assemble the measurement control message SDU frommultiple individually received PDUs. The UE 202 can know an SFN valuefor each received PDU. As shown by the time line 900 in FIG. 9, the UE202 can calculate an extended CFN for the first received PDU 902 and forthe last received PDU 904 of the measurement control message SDU. Due toretransmissions, the last received PDU can differ from the final PDU inthe reassembled measurement control message SDU. If the differencebetween the extended CFN value for the last received PDU and theextended CFN value for the first received PDU equals or exceeds 256frames (i.e. the roll over modulo value), then the CFN values at the UE202 can have “rolled over” during the time to receive the completemeasurement control message SDU. In this case, the RNS 216 can havealready started compressed mode by the time the UE 202 receives thefinal PDU. The UE 202 can enter compressed mode as soon as possible ifthe RNS 216 has already started compressed mode to minimize errors andmaximize overlap of compressed mode intervals on both sides of theconnection. While the above calculation can use the extended CFN valuefor the last received PDU 904, the UE 202 can also use a “current”extended CFN value to compare if the time elapsed between receiving thefirst PDU of the measurement control message SDU and the “current” timeequals of exceeds the rollover time of 256 frames.

As described above, when the time to receive all of the PDUs in themeasurement control message SDU equals of exceeds 256 frames, the localCFN counter can roll over. When the total time to receive all PDUs forthe measurement control message SDU is less than 256 frames, the time tostart compressed mode can also occur before the final PDU is received,particularly if the RNS 216 requests to start compressed mode in a framethat occurs soon after the first PDU is sent. As the RNS 216 canrecognize that the local CFN counter at the UE 202 can roll over after256 frames, the RNS 216 will not request in the measurement controlmessage SDU that the compressed mode start at a time longer than 256frames in the future. The UE 202 can calculate an extended CFN value 906for a future frame in which the compressed mode should start based onthe received CFN value in the measurement control message SDU. The UE202 can determine a difference between the calculated extended CFN value906 for the future start frame and the extended CFN value for the firstreceived PDU 902. If the difference is equal to or greater than 256,then the actual frame in which to start the compressed mode can occur inthe past. In this additional case, the RNS 216 can also have alreadystarted compressed mode by the time the UE 202 receives the final PDU.Again the UE 202 can enter compressed mode soon after detecting that theactual frame to enter compressed mode has passed to partially aligncompressed mode time intervals with the RNS 216.

FIG. 10 illustrates a UE 202 and RNS 216 with partially alignedcompressed mode time intervals. The UE 202 can detect if a compressedmode start frame, as specified by the time indication in the measurementcontrol message 1002 from the RNS 216, can occur in the past. The UE 202can enter compressed mode as soon as possible after receiving thecomplete measurement control message 1002, as indicated in FIG. 1000, tomaximize overlap of compressed mode time intervals at the UE 202 and theRNS 216. The time interval of non-overlap, i.e. from when the RNS 216starts compressed mode to when the UE 202 starts compressed mode, canstill produce errors, but this error prone time segment 1004 can beenminimized in length by the immediate action of the UE 202. The UE 202and the RNS 216 can both transmit using compressed mode during a timesegment 1006 that has a maximized time overlap. The UE 202 can determinewhen to stop compressed mode based on parameters supplied by the RNS 216in the measurement control message 1002. As the UE 202 can know whencompressed mode started locally at the UE 202, the UE 202 can endcompressed mode at the same time as the RNS 216 ends compressed mode.The compressed mode time segment at the UE 202 can be shorter thanspecified by parameters in the measurement control message 1002.

FIG. 11 outlines a method for controlling a configuration time change ina mobile wireless communication device. In step 1102, a mobile wirelesscommunication device, connected to a wireless network in a firstconfiguration mode, can receive a control message from a radio networksubsystem in the wireless network at a local receive time. The mobilewireless communication device, in step 1104, can extract a timeindication from the received control message. In step 1106, the mobilewireless communication device can use the extracted time indication andthe local time at the mobile communication device when the controlmessage was received to determine a local start time. The local starttime can indicate when the mobile wireless communication device canchange configurations. In step 1108, the mobile wireless communicationdevice can reconfigure to a second configuration mode based at thedetermined local start time.

While the preceding description discusses entering and exiting acompressed mode, the same method can be applied to determine when tostart a reconfiguration change requested by the RNS 216 to the UE 202 ina reconfiguration control message. If the reconfiguration controlmessage specifies a frame using a CFN, then the same “roll over” issuedescribed for the measurement control message can also occur on a noisycommunication link that can delay complete reception by the UE 202 ofthe reconfiguration control message.

Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer program productencoded as computer program code in a non-transitory computer readablemedium. The non-transitory computer readable medium is any data storagedevice that can store data which can thereafter be read by a computersystem. Examples of the non-transitory computer readable medium includeread-only memory, random-access memory, CD-ROMs, DVDs, magnetic tape andoptical data storage devices. The computer program product can also bedistributed over network-coupled computer systems so that the computerprogram code is stored and executed in a distributed fashion.

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination. Theforegoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the invention.However, it will be apparent to one skilled in the art that the specificdetails are not required in order to practice the invention. Thus, theforegoing descriptions of specific embodiments of the present inventionare presented for purposes of illustration and description. They are notintended to be exhaustive or to limit the invention to the precise formsdisclosed. It will be apparent to one of ordinary skill in the art thatmany modifications and variations are possible in view of the aboveteachings.

The embodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, to therebyenable others skilled in the art to best utilize the invention andvarious embodiments with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. Computer program product encoded in anon-transitory computer readable medium configured to reconfigure amobile wireless communication device connected to a wireless network,the computer program product comprising: computer program codeconfigured to receive a control message at a local receive time from aradio network subsystem in the wireless network; computer program codeconfigured to extract a time indication for starting a configurationmode change in a first configuration mode, where the time indication isextracted from the received control message; computer program codeconfigured to determine a first local frame counter value for a firstreceived frame in the received control message based on a local framecounter, where the local frame counter is configured to rollover at apredetermined number of frames; computer program code configured todetermine a second local frame counter value for a last received framein the received control message based on the local frame counter; andcomputer program code configured to reconfigure the mobile wirelesscommunication device to a second configuration mode at a reconfigurationstart time when a difference between the second local frame countervalue and the first local frame counter value is greater than thepredetermined number of frames.
 2. The computer program product asrecited in claim 1 wherein the predetermined number of frames is equalto a transmission gap pattern length.
 3. The computer program product asrecited in claim 1, wherein the computer program code configured toreconfigure the mobile wireless communication device to the secondconfiguration mode at the reconfiguration start time is configured toprovide a time interval of mismatched configuration modes between themobile wireless communication device and the wireless network bounded bythe extracted time indication and the reconfiguration start time.
 4. Thecomputer program product as recited in claim 1, further comprising:computer program code configured to determine a time interval value froma set of parameters extracted from the received control message; andcomputer program code configured to reconfigure the mobile wirelesscommunication device back to the first configuration mode and at a localend time based on the determined time interval value and on the localreceive time when the control message is received by the mobile wirelesscommunication device.
 5. The computer program product as recited inclaim 4, wherein the computer program code configured to reconfigure themobile wireless communication device back to the first configurationmode at the local end time provides a time interval of overlappingmatched configuration modes between the mobile wireless communicationdevice and the wireless network bounded by the reconfiguration starttime and the local end time.
 6. The computer program product as recitedin claim 1, further comprising: computer program code configured tocontrol a transceiver in the mobile wireless communication device totransmit and receive messages as a series of consecutive frames, whereinthe second configuration mode includes computer program code configuredto transmit or receive at least one compressed frame having atransmission gap and at least one uncompressed frame having notransmission gaps.
 7. The computer program product as recited in claim6, wherein the control message includes a plurality of frames; and thelocal receive time is a value for the local frame counter when the finalframe of the control message is correctly received by the mobilewireless communication device.
 8. A method to reconfigure a mobilewireless communication device connected to a wireless network, themethod comprising the mobile wireless communication device: receiving acontrol message at a local receive time from a radio network subsystemin the wireless network; extracting a time indication for starting aconfiguration mode change in a first configuration mode, where the timeindication is extracted from the received control message; determining afirst local frame counter value for a first received frame in thereceived control message based on a local frame counter, where the localframe counter is configured to rollover at a predetermined number offrames; determining a second local frame counter value for a lastreceived frame in the received control message based on the local framecounter; and reconfiguring the mobile wireless communication device to asecond configuration mode at a reconfiguration start time when adifference between the second local frame counter value and the firstlocal frame counter value is greater than the predetermined number offrames.
 9. The method as recited in claim 8, wherein the predeterminednumber of frames is equal to a transmission gap pattern length.
 10. Themethod as recited in claim 8, wherein reconfiguring the mobile wirelesscommunication device to the second configuration mode at thereconfiguration time provides a time interval of mismatchedconfiguration modes between the mobile wireless communication device andthe wireless network bounded by the extracted time indication and thereconfiguration start time.
 11. The method as recited in claim 8,further comprising the mobile wireless communication device: determininga time interval value from a set of parameters extracted from thereceived control message; and reconfiguring the mobile wirelesscommunication device back to the first configuration mode and at a localend time based on the determined time interval value and on the localreceive time when the control message is received by the mobile wirelesscommunication device.
 12. The method as recited in claim 11, whereinreconfiguring the mobile wireless communication device back to the firstconfiguration mode at the local end time provides a time interval ofoverlapping matched configuration modes between the mobile wirelesscommunication device and the wireless network bounded by thereconfiguration start time and the local end time.
 13. The method asrecited in claim 8, further comprising the mobile wireless communicationdevice: controlling a transceiver in the mobile wireless communicationdevice to transmit and receive messages as a series of consecutiveframes, wherein the second configuration mode includes transmitting orreceiving at least one compressed frame having a transmission gap and atleast one uncompressed frame having no transmission gaps.
 14. The methodas recited in claim 13, wherein the control message includes a pluralityof frames, and the local receive time is a value for the local framecounter when the final frame of the control message is correctlyreceived by the mobile wireless communication device.
 15. A mobilewireless communication device configured to operate within a wirelessnetwork, the mobile wireless communication device comprising: a wirelesstransceiver; a processor coupled to the wireless transceiver; and anon-transitory computer-readable medium comprising one or moreinstructions that, when executed by the processor, cause the mobilewireless communication device to: receive a control message at a localreceive time from a radio network subsystem in the wireless network;extract a time indication for starting a configuration mode change in afirst configuration mode, where the time indication is extracted fromthe received control message; determine a first local frame countervalue for a first received frame in the received control message basedon a local frame counter, where the local frame counter is configured torollover at a predetermined number of frames; determine a second localframe counter value for a last received frame in the received controlmessage based on the local frame counter; and reconfigure the mobilewireless communication device to a second configuration mode at areconfiguration start time when a difference between the second localframe counter value and the first local frame counter value is greaterthan the predetermined number of frames.
 16. The mobile wirelesscommunication device as recited in claim 15, wherein the predeterminednumber of frames is equal to a transmission gap pattern length.
 17. Themobile wireless communication device as recited in claim 15, whereinreconfiguring the mobile wireless communication device to the secondconfiguration mode at the reconfiguration time provides a time intervalof mismatched configuration modes between the mobile wirelesscommunication device and the wireless network bounded by the extractedtime indication and the reconfiguration start time.
 18. The mobilewireless communication device as recited in claim 15, wherein the one ormore instructions, when executed by the processor, further cause themobile wireless communication device to: determine a time interval valuefrom a set of parameters extracted from the received control message;and reconfigure the mobile wireless communication device back to thefirst configuration mode and at a local end time based on the determinedtime interval value and on the local receive time when the controlmessage is received by the mobile wireless communication device.
 19. Themobile wireless communication device as recited in claim 18, whereinreconfiguring the mobile wireless communication device back to the firstconfiguration mode at the local end time provides a time interval ofoverlapping matched configuration modes between the mobile wirelesscommunication device and the wireless network bounded by thereconfiguration start time and the local end time.
 20. The mobilewireless communication device as recited in claim 15, wherein the one ormore instructions, when executed by the processor, further cause themobile wireless communication device to: control a transceiver in themobile wireless communication device to transmit and receive messages asa series of consecutive frames, wherein the second configuration modeincludes transmitting or receiving at least one compressed frame havinga transmission gap and at least one uncompressed frame having notransmission gaps.
 21. The mobile wireless communication device asrecited in claim 20, wherein the control message includes a plurality offrames, and the local receive time is a value for the local framecounter when the final frame of the control message is correctlyreceived by the mobile wireless communication device.